Grinding mill



Aug. i3, i946; L.. M. BARKER E'rAL GRI-NDING MILL Filed Jan. *13,* 1 9l5:5

IN VEN TORS. .LNE MBAR/(Ear EATAN @Lew/S Patented Aug. 13, 1946 GRINDINGMILL Lyle lVL. Barker and. Evan. G.. Lewis,l Ajo, Ariz., assignors. toPhelps Dodge Corporation New York; NL Y., a corporation AofiNew YorkApplication January 13, 1943; Serialltlo..432,200.v`

This invention relates to grinding mills in which the commi-notion. oforel orY other material iseffected, by the grinding action of a massofmoving balls, pebbles, or thelike, within arotating cylinder, and` inwhich thecomminuted-y materialis discharged-through a grated portion ofthe-cylinder. In. mills ofI this type the` pluggingV of the grateopenings by worn grinding media, larger particles of ore, or the likeconstitutes afsource of considerable. annoyance, necessitates loss oroperating time in repeated cleaning of the grates, and results in.substantial. diminutionl of mill capacity and eiilciency.

The prime object of thepresent inventionis to provide a grated dischargeportion ofjagrinding millv which enables ready egress of groundmaterials, worn grinding meda, or other materials having certain maximumdimensionswithout the objectionable clogging tendencies exhibited inprior constructions. The invention provides a mill discharge endwhichfulfills this. purpose in aparticularly simple. and eiectivemanner;and, which enables the advantagesof millsofY the type, mentioned. to beutilized fullywithoutinterferenceby objectionable plugging. of' theldischarge grates.

Other features andvadvantages ofthe invention, will be hereinafter.described. and claimed. y

In the accompanying drawing:

liig. 1. is a fragmentary elevation, as viewed from the inside, showinga. portion. of. the discharge end-of agrinding.milllembodyingoneform.

persons familiar with the art, we will describe.

particularly only thedischarge endof the mill..

Referring to the, drawing, 2 designates the cylindrical shell or mainbody portionof theigrind-- ing mill, and. 3 the head. which closesthedischargeendv of said. shell. Secured to said` head 3 i's the customarycenterpiece. 4.which, as shown,

may include a passage 5 servingV as. an. observa--v tion port and asa.point of addition of balls or other grinding media. Said centerpiecealso has. formed therein a diversion passage. Ivfor the millproduct.Thev shell 2..is.provided.with a-lining 1 of suitable refractorymaterial. At center end liner, which may be of. formand material: bestadapted for grinding conditions, isindicated at: 8'; while othersuitable end liners, disposed outwardly from saidliner', areshown at 9andlll; Pulpli-fter` elements IIA of conventional fermA are also shown;

In carrying` outy our invention, We form discharge slots; such afsareshownat I2, by mounting elements- I3 of rubber'or other suitableresilient material inr suitably spaced` relationship. Inv theembodiment. illustrated; these resilient elements I3' are-fmoulntedI in7cut out portions of the' liners 8, 9., andfIIl; and are attachedto'and'i-lrmly mai-ntained inposition by backing plates Iwelded orotherwiselsuitably secured.- to said'liners or tothe dischargehead 3. Asshown, said backing plates i4 terminate short of the edges` ofthefrubber elements= I3 tot enable iiexurefof` saidedges-v tothe extent`desired. l'

We.Y furthermore, sofspace. theliners 8, 3, and Iwit-h respect toeachfother asto form between them channels |15-0f such width or formas to'permit:ready movement within saidchannels of the largestV ball, or othergrinding member in the charge: The linersiwhich form-the' channel alsofunctionftoprevent direct action of any large portionoii thecharge ofgrinding members upon the rubber elements I3.

It williV beiV understood that the cylinder '2, lining- 'I-, head 3.,centerpiece= 4, liners 8, 9; and IIB, and lifters- I.I arefsuitablyYfastened together to ro*- tate in` unison inthe operationof the mill'.lThe lif-ters Iltare integral,4 with the heade3, which is suitablysecured tothey cylinder 2 and center-piece- 4.; while' the liners 83 8,and IUA andV associated backing plates i4? are suitably fastenedr to theli-fters-r II.

In assemblingl said liners andassociated parts, the liner I0- mayy firsthave attachedv thereto a rubber element I3 and aback-ingpla-te I4.. Thelatter may be fastened: toY the liner by suitable boltsorbywelding.Thereafter, said-liner II) may be. inserted intofthe. head 3 and securedtherein by a suitably tight t, or by welding or otherwise fasteningy thebacking plate I-@f tov the liftern II. Liner 8, after having a rubberelement I 3- and backingplate I4 attached thereto may thenv be placed inthe desired' position onY the lifters H and fastened..in. positionthrough said plateV It. Said liner 8 may also,r asshown, have. a similarplate t4 interposedY between said liner 'and said lifter and suitablyfastened.v thereto- Then. the liner9, after having,V rubber elements I3andbacking, plate. Ill attached thereto; is placed. Von the litters I.I`inthe desired spaced. relationship with respect to? the. liners-8 andlill; following which said liner 9 is securedtmsaid litters III throughsaid plate I4 in any desired manner. The cenprovide backing for therubber elementsyIB by extending beyond the liners, but also that saidplates, by terminating short of the edges 1 of said elements` providefor controlled exure of said.

edges. Said plates may be so positioned with respect to said edges as tocontrol iiexure of the' latter to the desired extent.

A ball mill equipped with a discharge end em-v bodying our invention hasbeen found to maintain full efliciency for a prolonged period, withoutinterruption and without any evidence of plugging. The freedom from thenecessity of periodic cleaning of grates, and the gains in capacity andeiiiciency resulting from lthe avoidance of grate clogging, aresubstantial and important advantages.

While we do not assert any particular Atheory as controlling orconclusive with respect to the advantages attained by our'inven'tion,WeV believe thatone vreason for the attainment of those advantages isthe capability of the resilient elements I3 to dislodge, or feed backinto the cylinder 2, oversize particles'which may become momentarilylodged between said elements. In that connection, it is to be noted thatthe width of the slot t2 between adjacent rubber elements I3 The backingplates I 4 may be Vof rigid material such as steel, or of materialresilient and iiexible in character, such as conveyor belting.

The terms and expressions which We have employed are used as terms ofdescription and not of limitation, and We have no intention, in the useof such terms and expressions, of excluding any equivalents of thefeatures Vshown and described or portions thereof, but recognize thatvarious modiiications are possible within the scope of the inventionclaimed.

We claim:

1. Grinding mill discharge means comprising members dening a channel, aplurality of resilient elements mounted on said members at the base ofsaid channel and defining a slot, and backing means extending beyondsaid members over portions of said resilient elements and tersaidresilient elements, said backing means exis fixed only so long as saidelements are not rubber, Vand its Walls are constantly parallel when innormal position. However, upon i'lexure of the rubber elements 'thewidth of the slot increases, and the walls diverge in the direction ofdeformation. Now, when a particle is presented ments I3, that particlecan pass only if its minimum dimension is such that it'may enter theslot under the condition of maximum slot deformation. If the forcestending to move the particleA into the slot are not adequate for thepurpose, the reiiex of the rubber elements rejects it when'the forcesare removed. It is also pos-Y sible that particles of certain shanemaybe temporarily retained in the slot and that the flexing anddeformation of the rubber elements resulting from the subsequent entryof other particles accomplishes their release. But whatever may be thetheory, We have found the construction illustrated to be highlyeffective in obviating clogging, with the consequent advantageshereinbefore referred to.

The elements I3 may be of rubber or any other material having thedesired strength. flexibility, and resiliency. Fabric-reinforced rubber,conveyor-belt `cover stockrubber, orrthe so-called "iioating-stockrubber are examples of suitable materials which may be employed.

We believe also that the provision of channels I5 oiv such width or formasto permit ready movement within them of the largest ball, or otherelement in the grinding charge. augments the effectiveness of theinvention by enabling grinding elements to act upon particles in thechannels adjacent the'slots.

tending 'over portions of said elements but terminating short of theslot forming edges of said elements.H Y

3. Grinding mill discharge means comprising members defining a" channelin communication with the grinding chamber of the mill, said channelbeing of such form as to permit'free movement of grinding elementswithin it, resilient elements disposed at the base of said channel anddefining a slot at said base, and backing means extending intooverlapping relation with portions of said resilient elements and withportions of said channel, said backing means terminating short of theslot-dening edges of said elements.

4.,Discharge means for a grinding mill of the type comprising arotatable casing providing a chamber for material to be ground, saiddischarge means comprising members defining a channel at a slot I2 andforced against the adjacent elefor` receiving material from saidchamber, and means defining a slot at the discharge side of saidchannel, said means comprising a strip of resilient material secured atone edge to one of said channel-defining members, said strip having Aasubstantial portion extending beyond said member and terminating in afree edge in said channel, said portion being freely movable inv adirection outwardly from said channel in response to pressureexertedthereon by material within said channel.

5. Discharge means for a grinding mill of the type comprising arotatable casing providing a chamber for material to be ground, saiddischarge means comprising members defining a channel for receivingmaterial from said chamber, and means defining a slot at the dischargeside of said channel, said means comprising a pair of strips ofresilient materialeach secured at one edge to aA corresponding one ofsaid channel-denng members, each of said resilient strips having asubstantial portion extending beyond the corresponding ychannel-deliningmember and terminatingin a free edge in said channel, each of saidextending portions of said strips being freely mov. able in a directionoutwardly from said channel in response to pressure exerted thereon bymaterial within said channel. s

vE5. Discharge meansfor a grinding mill of the type comprising arotatable casing providing a chamber for material to be ground, saiddischarge means comprising members defining a channel for receivingmaterial from said chamber, said channel converging from its receivingside toward its discharge side, and means defining a slot at thedischarge side of said channel, said means comprising a strip ofresilient material secured at one edge to one of said channel-deningmembers, said strip having a substantial portion extending beyond saidmember and terminating in a free edge in said channel, said portionbeing freely movable in a direction outwardly from said channel inresponse to pressure exerted thereon by material within said channel,said channel being of sufficient size to enable free movement ofgrinding elements therewithin.

'7. Discharge means for a grinding mill of the type comprising arotatable casing providing a chamber for material to be ground, saiddischarge means comprising members defining a channel for receivingmaterial from said chamber, said channel converging from its receivingside toward its discharge side, and means defining a slot at thedischarge side of said channe1, said means comprising a pair of stripsof resilient material each secured at one edge to one of said channe1-deiining members, each of said strips having a substantial portionextending beyond the corresponding channel-dening member and terminatingin a free edge in said channel, each of said extending portions of saidstrips being freely movable in a direction outwardly from said channelin response to pressure exerted thereon by material Within said channel,said channel being of such size as to enable free movement of grindingelements therewithin.

8. Discharge means for a grinding mill of the type comprising arotatable casing providing a chamber for material to be ground, saiddischarge means comprising members dening a channel for receivingmaterial from said chamber, and means defining a slot at the dischargeside of said channe1, said means comprising a strip of resilientmaterial secured at one edge to one of said channel-defining members,said strip having a substantial portion extending beyond said member andterminating in a free edge in said channel, and backing means extendingbeyond said channel-denning member over a portion of said strip andterminating short of said free edge, the portion of said strip beyondsaid backing member being freely movable in a direction outwardly fromthe channel in response to pressure exerted thereon by material Withinsaid channel.

LYLE MQ'BARKER. EVAN G. LEWIS.

